Quantum effects in a half-polarized pyrochlore antiferromagnet
Abstract
We study quantum effects in a spin-3/2 antiferromagnet on the pyrochlore lattice in an external magnetic field, focusing on the vicinity of a plateau in the magnetization at half the saturation value, observed in CdCrO, and HgCrO. Our theory, based on quantum fluctuations, predicts the existence of a symmetry-broken state on the plateau, even with only nearest-neighbor microscopic exchange. This symmetry broken state consists of a particular arrangement of spins polarized parallel and antiparallel to the field in a 3:1 ratio on each tetrahedron. It quadruples the lattice unit cell, and reduces the space group from to . We also predict that for fields just above the plateau, the low temperature phase has transverse spin order, describable as a Bose-Einstein condensate of magnons. Other comparisons to and suggestions for experiments are discussed.
Cite
@article{arxiv.cond-mat/0510202,
title = {Quantum effects in a half-polarized pyrochlore antiferromagnet},
author = {Doron L. Bergman and Ryuichi Shindou and Gregory A. Fiete and Leon Balents},
journal= {arXiv preprint arXiv:cond-mat/0510202},
year = {2007}
}